Vibration cylinder for compacting concrete

ABSTRACT

The invention relates to a vibration cylinder for an immersion vibrator suited for compacting concrete. The vibration cylinder comprises a housing, which can be closed at one end and inside of which an unbalanced shaft that can be driven is radially and axially guided and supported by antifriction bearings. An antifriction bearing that serves to axially support the unbalanced shaft is supported on the housing in at least one axial direction by a damping element that can be subjected to a high level of deformation work. The damping element can be a shaped element made of an elastomer or plastic

[0001] The present invention relates to a vibration cylinder for compacting concrete according to the preamble of patent claim 1, having a tube-shaped housing that is closed at one end, in which an imbalance shaft that can be driven is guided and mounted by roller bearings.

[0002] Known vibration cylinders, used in what are known as internal vibrators, have a steel housing that is either closed at one end by an integrally formed base, in the manner of a bottle, or is made of a tube piece with an inserted base part. A standardly flexible, hose-type element is fastened to the vibration cylinder as a guide element. Inside the vibration cylinder, there is situated an imbalance shaft that bears an imbalance mass; this shaft can be driven by a motor that is likewise situated in the vibration cylinder.

[0003] Due to the high loading of the bearing points resulting from the centrifugal force of the imbalance mass, the radial guiding of the roller bearings that support the shaft normally takes place directly in the tube-shaped housing area. In the axial direction, at least one roller bearing of the imbalance mass lies directly on a shoulder that is formed on the housing tube or is formed by the inserted base part. In normal operation, this support shoulder is loaded axially only by the weight of the imbalance shaft, and is possibly also loaded statically by the initial tension of a length-compensating spring.

[0004] In rough operation on construction sites, it often happens that after the termination of compacting work vibration cylinders are thrown from a scaffold from a great height. If in such a case the vibration cylinder strikes a hard surface (for example, a concrete slab) in approximately vertical fashion, i.e., in the axial direction of the imbalance shaft, the mass forces result in extreme shock and impact loadings, at least of the roller bearings used for axial bearing. Similar loads can also occur during compacting work, if the concreting is carried out in layers and the housing of the vibration cylinder impacts the already-hardened surface, or reinforcement iron, from a height of several meters.

[0005] These strong shock and impact loads cause damages to the edges of the inner and outer rings of roller bearings, to the roller elements, and to their tracks. This not only reduces the lifespan, but also bearing parts are often destroyed, resulting in a complete failure of the vibration cylinder.

[0006] The present invention is based on the object of taking into account these strong stresses, and reducing or eliminating their effects.

[0007] According to the characterizing part of patent claim 1, the solution of this problem is that a roller bearing used for the axial bearing of the imbalance shaft is supported in at least one axial direction by a damping element on the housing that is suitable for accepting large-scale deformation work.

[0008] The damping element is usefully formed as a spring element, and, through its deformation when there is an axial impact on the vibration cylinder, absorbs at least a part of the mass forces, thus reducing the shock stress on the bearing, and thus preventing damage to bearing parts.

[0009] Various embodiments of the damping element are possible, all of which are distinguished by a good deformability, such as for example a large-volume molded element made of an elastomer, [or] molded elements made of plastic, whereby the molded elements can be formed for example as a cushion or as a ring. Springs, such as screw springs, spring washer sets, or annular springs, can also be used as damping elements.

[0010] The present invention is explained in more detail below on the basis of the following description of exemplary embodiments.

[0011]FIG. 1 shows a section through a vibration cylinder according to the present invention, having a ring as a molded damping element,

[0012]FIG. 2 shows a section similar to that shown in FIG. 1, with a cushion-type molded element,

[0013]FIG. 3 shows a section similar to that shown in FIG. 1, having a screw spring as a damping element,

[0014]FIG. 4 shows a section similar to that in FIG. 1 having a damping spring washer set, and

[0015]FIG. 5 shows a section similar to that shown in FIG. 1, having an annular spring as a damping element.

[0016] The specific embodiments shown in the Figures differ from one another only in the damping element (spring element) used therein, and agree with one another in their remaining constructive elements.

[0017] To a tube-shaped guide element (not shown), there is joined a vibration cylinder 12 having a housing 14 that is closed at its lower end, as well as a housing tube 10 that is connected thereto and that encloses a drive motor. Alternatively, vibration cylinders are also known having a tube-shaped housing that is sealed at the free end by a sealing cap. The following constructive examples are equally applicable to such vibration cylinders.

[0018] In housing 14, an imbalance shaft 16 that can be driven so as to rotate is supported by an upper roller bearing 18 and a lower roller bearing 20; between these two bearings 18 and 20, an imbalance mass 22 is connected with shaft 16 by screws 24 and 26. Imbalance shaft 16 and imbalance mass 22 can also be connected with one another in a known manner. A one-piece manufacture or a loose connection is also possible. A length-compensating spring 28 is also fixed between shaft 16 and roller bearing 20.

[0019] Between a shoulder 30 formed at the lower end of housing 14 in the interior of the housing and the outer ring of lower roller bearing 20, there is situated a damping element 32, which in FIG. 1 is fashioned as a ring and is made of an elastomer or a plastic.

[0020] In FIG. 2, damping element 32 is an elastomer cushion, while in FIG. 3 it is a screw spring, in FIG. 4 it is a spring washer set, and in FIG. 5 it is an annular spring.

[0021] In the case of an impact outside roller bearing 20, elastomer cushion 32 according to FIG. 2 can also cushion the front side of imbalance shaft 16, if this side comes into contact with elastomer cushion 32. 

1. A vibration cylinder for concrete compacting, comprising a housing that can be sealed at one end, in which an imbalance shaft that can be driven is guided and mounted radially and axially by roller bearings, wherein a roller bearing used for the axial support of the imbalance shaft is directly supported in at least one axial direction by a damping element on the housing that is suitable for accepting large-scale deformation work.
 2. The vibration cylinder as recited in claim 1, wherein the damping element is a molded element made of an elastomer.
 3. The vibration cylinder as recited in claim 1, wherein the damping element is a molded element made of plastic.
 4. The vibration cylinder as recited in claim 2, wherein the molded element is a ring.
 5. The vibration cylinder as recited in claim 2, wherein the molded element is a cushion.
 6. The vibration cylinder as recited in claim 1, wherein the damping element is a screw spring.
 7. The vibration cylinder as recited in claim 1, the damping element is a spring washer set.
 8. The vibration cylinder as recited in claim 1, wherein the damping element has at least one annular spring. 